There are scenarios where a user with a user's equipment can negotiate with a telecommunication network, via a signalling layer, requirements on quality of service (hereinafter QoS) for a number of services, which are in fact carried through a separate bearer or connectivity layer provided by an access network.
For instance, a first scenario may be where the user negotiates requirements on QoS with an IP Multimedia Subsystem (hereinafter IMS), as specified in 3GPP TS 23.228 V7.3.0, whereas the services are actually carried through a General Packet Radio Service (GPRS) connectivity layer. In this first scenario, a proxy Call Session Control Function (hereinafter P-CSCF) is an entry point to the IMS and is located at the control plane thus aware of requirements on QoS. On the other hand, the bearer layer in this first scenario is built up through a connection path established between the user's equipment (hereinafter UE), a Serving GPRS Support Node (hereinafter SGSN), and a Gateway GPRS Support Node (hereinafter GGSN).
A second scenario may be where the user negotiates requirements on QoS with a streaming server for video download services, whereas the services are actually carried through a Wireless Local Area Network (WLAN) connectivity layer. In this second scenario, the streaming server is the entity in charge of negotiating the requirements on QoS with the UE, and is located at the control plane; whereas the bearer layer is built up through a connection path between the UBE a WLAN Access Point (hereinafter WLAN AP), a WLAN Access Gateway (hereinafter WAG), and a Packet Data Gateway (hereinafter PDG).
New scenarios might be apparent by having different combinations of signalling layer at the control plane with bearer layer at the traffic plane.
In this context, a bearer or connectivity layer is a media transport, capable of carrying a plurality of Internet Protocol (hereinafter IP) flows, and takes place at the traffic plane. An IP flow is a unidirectional flow of IP packets with the same source IP address and port number, the same destination IP address and port number and the same transport protocol. An IP flow is thus used to transmit IP packets between an origin and a destination. Each IP flow may be associated with a service, and several IP flows may be associated with the same service. For the purpose of the present invention, a service is represented by at least one service data flow (hereinafter SDF) which consists of one or more IP flows.
A common architecture called Policy and Charging Control (hereinafter PCC) is nowadays developed under 3GPP TS 23.203 V0.4.0, which is supposedly addressing all different types of access networks.
In accordance with 3GPP TS 23.203, this PCC includes a Policing and Charging Enforcement Function (hereinafter PCEF) in charge of SDF detection, policing enforcement and charging functionality. The PCEF is included in the traffic plane and supports the connectivity or bearer layer between originating and destination user equipments.
Also in this PCC architecture, there is a Policing and Charging Rules Function (hereinafter PCRF) in charge of providing network control for the above SDF detection, policing enforcement decision-based and charging decision-based functionality, as well as for QoS. This PCRF is preferably located in an intermediate entity enabled to communicate with a server in the control plane and with the above PCEF in the traffic plane.
Apart from the PCEF and PCRF, the PCC architecture also includes an application function (hereinafter AF) for offering applications that require control of the IP bearer resources. In particular, the AF may reside in or be an integral part of a server in the control plane aware of negotiated requirements on QoS. The AF communicates with the PCRF to transfer dynamic session information required for PCRF decisions.
The basic PCC architecture described hereinbefore is suitable for being applied in scenarios where services are negotiated through the signalling layer, between the user equipments and servers in the control plane; whereas said services are actually carried through the connectivity or bearer layer, between originating and destination user equipments. In such scenarios, the PCRF makes decisions to enforce what has been negotiated through the signalling layer into the connectivity layer and, in the other way around, the PCRF must advertise the signalling layer of any relevant event in the connectivity layer that might affect the desired quality of any such service. However, PCC architecture is not able to detect any change on the status of each particular media used per SDF basis.